System off mode still drawing 200uA. how to switch off the saadc and pull high the saadc pins?

RE: System off mode still drawing 200uA. how to switch off the saadc and pull high the saadc pins?

ctchong — Fri, 05 Jul 2019 15:48:28 GMT

Hi Jorgen,

Yes I measure the current with the debugger removed on my prototype board. With the debugger plugged in I could see a significant increase in current draw.

Thank you

RE: System off mode still drawing 200uA. how to switch off the saadc and pull high the saadc pins?

Jørgen Holmefjord — Fri, 05 Jul 2019 11:57:24 GMT

It could be that the debugger put the chip in debug mode. You should measure the current without debugger connected. In debug mode, CPU and clocks will be running.

RE: System off mode still drawing 200uA. how to switch off the saadc and pull high the saadc pins?

ctchong — Fri, 05 Jul 2019 10:19:58 GMT

Hi Jorgen,

Thank you for your reply. Do I need to configure/set the SWDCLK and SWDIO as well ?

It seems like my chip is not going to system off mode. It resets when I plug in the swd.

Thank you

Best regards

Chong

RE: System off mode still drawing 200uA. how to switch off the saadc and pull high the saadc pins?

Jørgen Holmefjord — Thu, 04 Jul 2019 13:32:57 GMT

[quote user="ctchong"]Will the BSP events prevent the chip to go into system OFF mode ? [/quote]

No, they should not. Entering System OFF mode will turn off all clock sources and only GPIO/NFC/LPCOMP/RESET can wake the chip. If bsp_btn_ble_sleep_mode_prepare() configures a floating pin as wakeup source (BSP buttons have not been initialized), this could cause the chip to wake right away. This will trigger a chip reset.

[quote user="ctchong"]Are there any checks to verify if the chip is in system OFF mode ? [/quote]

Only by measuring the current consumption of the chip. This should be ~300 nA. The function call will not return.

RE: System off mode still drawing 200uA. how to switch off the saadc and pull high the saadc pins?

Jørgen Holmefjord — Thu, 04 Jul 2019 13:32:57 GMT

[quote user="ctchong"]Will the BSP events prevent the chip to go into system OFF mode ? [/quote]

[quote user="ctchong"]Are there any checks to verify if the chip is in system OFF mode ? [/quote]

Only by measuring the current consumption of the chip. This should be ~300 nA. The function call will not return.

RE: System off mode still drawing 200uA. how to switch off the saadc and pull high the saadc pins?

Jørgen Holmefjord — Thu, 04 Jul 2019 13:32:42 GMT

[quote user="ctchong"]Will the BSP events prevent the chip to go into system OFF mode ?[/quote]

No, they should not. Entering System OFF mode will turn off all clock sources and only GPIO/NFC/LPCOMP/RESET can wake the chip. If bsp_btn_ble_sleep_mode_prepare() configures a floating pin as wake-up source (BSP buttons have not been initialized), this could cause the chip to wake right away. This will trigger a chip reset.

[quote user="ctchong"]Are there any checks to verify if the chip is in system OFF mode ? [/quote]

Only by measuring the current consumption of the chip. This should be ~300 nA. The function call will not return.

RE: System off mode still drawing 200uA. how to switch off the saadc and pull high the saadc pins?

ctchong — Thu, 04 Jul 2019 10:18:40 GMT

Hi Jorgen

Will the BSP events prevent the chip to go into system OFF mode ?

Are there any checks to verify if the chip is in system OFF mode ?

I have done the following to shut down to system OFF mode.

uint32_t err_code = bsp_indication_set(BSP_INDICATE_IDLE);
    APP_ERROR_CHECK(err_code);

    // Prepare wakeup buttons.
    err_code = bsp_btn_ble_sleep_mode_prepare();
    APP_ERROR_CHECK(err_code);
    nrfx_saadc_uninit();
    app_timer_stop(peroid_adc_timer_id);
     err_code = sd_power_system_off();
    APP_ERROR_CHECK(err_code);

Thank you

Best regards,

Chong

RE: System off mode still drawing 200uA. how to switch off the saadc and pull high the saadc pins?

Jørgen Holmefjord — Thu, 04 Jul 2019 09:18:19 GMT

Is it the nRF or external devices that draw this high current? The nRF will not draw this much current if it is in System OFF mode, so either it is not in this state, or there are external devices that draw current. All clock sources are stopped when the chip is put in System OFF mode.

RE: System off mode still drawing 150uA. how to switch off the saadc and pull high the saadc pins?

ctchong — Thu, 04 Jul 2019 04:19:23 GMT

Hi Jorgen,

Thank you for your help. It works but I realised that it doesn't help with my current consumption problem in sleep mode. I'm still getting 200uA of current draw at system mode off. I'm using BSP Events as well does it affect the sleep mode ?

My sensors have no voltage difference which I assume no current draw as well.

Thank you

Best regards,

Chong

RE: System off mode still drawing 150uA. how to switch off the saadc and pull high the saadc pins?

Jørgen Holmefjord — Wed, 03 Jul 2019 11:04:12 GMT

Hi,

After you uninit the SAADC, you can control the pins using GPIO HAL functions. Use GPIO pin number corresponding to the analog input, i.e. AIN0 = P0.02 (see nRF52840 Pin assignments):

nrf_gpio_cfg_input(2, NRF_GPIO_PIN_PULLUP)

Best regards,
Jørgen